Automotive frames and other metallic structures may make use of combinations of materials in order to obtain desirable characteristics of strength while simultaneously reducing weight. In this regard, it is known to utilize magnesium components in automotive vehicles and other structures where minimization of weight may be desirable. As will be appreciated, magnesium provides an excellent strength to weight ratio relative to materials such as structural steel.
In order to promote structural stability, magnesium components are often used in combination with components of steel or other metals. However, it has been found that if magnesium components are held in contacting relation to steel or other structural materials, the magnesium may tend to suffer from galvanic corrosion. Such corrosion arises due to the relative potential differences between the metals. As will be understood by those of skill in the art, the standard potential of a given metal is typically defined relative to that of a hydrogen electrode which is arbitrarily defined as zero. The potentials between metals are then determined by taking the absolute differences between their standard potential levels. A greater potential difference between metals promotes greater galvanic corrosion.
As will be appreciated, there is a substantial potential difference between iron and magnesium such that galvanic corrosion is actively promoted in regions of contact between those metals. It is known that the corrosion potential may be reduced by placing an isolating buffer metal with an intermediate potential between the magnesium and other metal components. In the past, buffer metals that have been utilized have been in the form of aluminum plates and inserts that provide spacing between the magnesium and the steel or other structural metal components. Plates have typically been attached using adhesive bonding techniques while inserts have been applied using press-in techniques. While these past protection systems have been functional, the adhesive-applied and press-in structures may be prone to becoming disengaged. Moreover, the application processes themselves may be laborious and time consuming.